Variable resistor



Dec. 1, I970 SHINICHI MURAKAMI 3,544,946

VARIABLE RESISTOR 2 Sheets-Shoot 1 Filed March 10, 1969 FIG, 2

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FIG. 3-

Dec. 1, 1970 SHINICHI MURAKAMI 3,544,946

VARIABLE RES I STOR Filed Mafch 10, 1969 2 Sheets-Sheet I N VEN TOR BY law UUUCWW United States Patent O 3,544,946 VARIABLE RESISTOR Shinichi Murakami, Hamamatsu-shi, Japan, assignor to Nippon Gakki Seizo Kabushiki Kaisha, Hamamatsushi, Japan, a corporation of Japan Filed Mar. 10, 1969, Ser. No. 805,722 Int. Cl. H01c 9/02 US. Cl. 338174 10 Claims ABSTRACT OF THE DISCLOSURE A variable resistor has a narrow housing, and a hand operable lever swingable in a plane extending in the lengthwise direction of said housing so as to control the resistance. A large number of variable resistors can be arranged in juxtaposition within a short distance in their transverse direction.

BACKGROUND OF THE INVENTION This invention relates to a variable resistor and more particularly to a miniature variable resistor employed mainly in the control equipment of electronic musical instruments.

The prior art miniature variable resistor had a wide housing and a hand operable shaft rotatable around its axis so as to control the resistance, and was therefore suitable to be utilized as a volume control for a transistorradio receiver. Nevertheless, said variable resistor was unfitted for use as a controller for varying the tone coloring effect of an electronic musical instrument, because the variable resistor lacked operability and installation of a large number thereof would require too much space. Namely, from technical requirements in design and musical performance, said instrument will have to be provided with a large number of controllers arranged in juxtaposition within a short distance, and a lever provided in each controller will also have to be swingable through a small range of angles in a plane perpendicular to a control panel.

SUMMARY OF THE INVENTION An object of this invention is to provide a variable resistor having a narrow housing, said housing being capable of being arranged in large numbers in juxtaposition within a short distance, and a hand operable lever swingable in a plane extending the lengthwise direction of said housing so as to be easily actuated.

Therefore, the variable resistor of this invention comprises a narrow housing of electric insulating material having an attachment face extending in the lengthwise direction thereof, an arcuate flat plate of electrical resistance material mounted on said attachment face, a stationary contacting member of electric conductive material mounted on said attachment fact in a manner to extend parallel to said resistance plate, an operating lever swingable over said attachment face and extending outside of said housing, and a movable slider of electric conductive material having two arms extending to the resistance plate and stationary contacting member, one of which has a contact element slidable on the surface of said resistance plate along the length thereof with the movement of said operating lever, and the other of which has a contact element slidable on the surface of said stationary contacting member with the movement of the aforesaid contact element.

In the arrangement, said stationary contacting member may be corrugated in its lengthwise direction so that the corresponding contact element is brought into the root portion of the corrugation thereof after passing over the crest portion so as to be stably positioned at said root. Accord- 3,544,946 Patented Dec. 1, 1970 ingly, the variable resistor involving such stationary corrugated contacting member enables the operator to find the extent of progressively varying the value of a resistor by the touch as well as by counting the number of clatterings caused by said operation.

BRIEF EXPLANATION OF THE DRAWINGS This invention will be understood more clearly from the following detailed description when taken in connection with the accompanying drawings, in which:

FIG. 1 is a side view of a variable resistor embodying this invention, partly broken away;

FIG. 2 is a cross-sectional view of the variable resistor taken along a line II-II of FIG. 1;

FIG. 3 is a plan view of said variable resistor;

FIG. 4 is a perspective view of a corrugated contacting member involved in said variable resistor;

FIG. 5 is a perspective view of the transverse arrangement of the variable resistors of the same type as that of FIGS. 1 to 4; and

FIG. 6 is a perspective view of the blocked portion of a housing involved in said variable resistor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A variable resistor 1 of this invention illustrated in the drawings is of miniature type. Said variable resistor 1 involves a narrow housing 2 of electric insulating material having an attachment face 3 extending in the lengthwise direction thereof. Said narrow housing is preferably made of synthetic resin such as a phenol resin, and comprises a flat side wall 2a, a stationary pillar 2b integrally formed with said fiat side wall 2a and disposed on the inside thereof in a manner to extend from the upper portion of said housing in the transverse direction of said housing, and a peripheral wall 2c integrally formed with the side wall 2a in a manner substantially to surround the hollow portion of the housing 2 except for the part near the pillar. Said narrow housing 2 further comprises a flat piece 4 of synthetic resin attached to the inside surface of the flat side wall 2a so that the attachment face 3 is separated into two parts 3a and 3b jointly forming a stepped portion in the hollow portion of the housing.

At the part 3a positioned on the flat piece 4 is disposed an arcuate flat plate of electrical resistance material such as carbon. In this embodiment, said arcuate flat plate consists of a carbon film coated on a Bakelite base. At the other part 3b positioned on the inner surface of the side wall 2a is disposed an arcuate stationary contacting member 6 of electric conductive material in such a manner that the stationary contacting member 6 and resistance plate 5 have arches parallel to each other, and the centers of circles represented by said arches are substantially superposed on that of the pillar. Said contacting member 6 is preferably corrugated in the lengthwise direction of said arch. Where the surfaces of the resistance plate 5 and stationary contacting member 6 are respectively extended to the areas which include the travelling loci of the contact portions of a movable slider (as explained hereinafter) respectively, the contours of the resistance plate and stationary contacting member may be of any shape different from, such as rectangular.

The variable resistor 1 also encloses a hand operable lever 7 of synthetic resin having a bore 7a formed at the intermediate portion thereof and rotatably fitting in with the pillar 2b so that the lever 7 is swung over said attachment face 3. One end portion of the lever 7 extends outside of the housing. To the other end portion of the lever 7 is attached a movable slider 8 of electric con ductive material having two arms 8a and 8b extending to the resistance plate and stationary contacting member respectively. One of said arms has acontact element 9 slidable on the surface of the resistance plate in a manner to travel along the length of said resistance plate. The other of the arms has a contact element slidable on the stationary contacting member '6 in a manner to be brought into the root portion 6a of the corrugation of said member 6 after passing over the crest portijon 6b so as to be stably positioned at said root. In this case, said contact elements 9 and 10 are pressed to the resistance plate and stationary contacting member respectively. The movable slider 8 is preferably made of copper alloy such as Phosphor bronze, beryllium copper and titanium copper, having a sufiicient elasticity to cause the elements 9 and 10 to contact the resistance plate and contacting member as tightly as possible.

Both blocked portions 11 on the peripheral wall 20 are respectively provided with a recess 12 extending from the upper surface of the housing into the block. A chamber 13 is formed in each of the blocks 11 in a manner to extend from the surface of the housing opposite to the side wall 2a into said block and across the intermediate portion of the recess 12. A hexagon nut 14 is contained in the chamber 13 and prevented from being rotated therein. Namely, said chamber 13- has a larger width than that of the recess 12 and is provided with the four inside walls 13a, 13b, 13c and 13d which define a partly hexagonal aperture adapted closely to fit the nut 14 into said chamber.

To the surface of housing 2 opposite to the side Wall 211 is attached a metal cover plate 15 for shielding the electric elements contained in the hollow portion of the housing 2 from harmful electric effect from the outside of the housing. Said cover plate 15 has a pair of clips 15a formed on both sides, which are engaged with the edges of the stages 16 formed on both sides of the housing 2 respectively.

In this embodiment, the lever 7 is provided with a protrusion 17 integrally formed at the inner end thereof. Said protrusion 17 is slidably pressed on the inner surface of the cover plate 15 by the elastic force of the movable slider 8, so that each of the contact elements can maintain its contact stress. The lever 7 is further provided with a boss 18, the top of which rotatably contacts the inner surface of the cover plate 15, whereby the lever is prevented from being moved in an axial direction of the pillar 2b.

The resistance plate 5, contacting member 6 and cover plate 15 are provided with a terminal or terminals indicated by the referential numerals 5a, 5b, 60, 15b and 21. The terminals 5a and 5b are connected to both ends of the arch of the resistance plate 5, while the terminal 60 is connected to one end of the arch of the stationary contacting member 6. The variable resistor is employed as a potentiometer by utilizing the terminal 60 and either one of the terminals 5a and 5b. The terminals 15b and 21 are intended to ground the variable resistor and also to cause inputs to be repeatedly supplied. The terminal 15b is integrally formed with the metal cover plate 15 and the terminal 21 is independently provided on the outer surface of the side wall 2a without electrical connection to any other members.

FIG. 5 indicates the variable resistors of the same type as that of FIGS. 1 to 4, so arranged as to afford convenience in designing and manipulating a device for presetting stops involved in an electronic musical instrument. An attachment panel 19 has a plurality of rectangular apertures 19a systematically arranged thereon and a plurality of pairs of through bores 19b. In this arrangement, a large number of variable resistors are arranged in juxtaposition in their transverse direction and in three rows. Furthermore, these variable resistors are attached to the back of said attachment panel 19 by screwing a set screw 20 through the bore 19b and recess 12 into the nut 14, in a manner to put out the end portion of the lever 7 through the aperture 19a. This attachment is easily accomplished, as the nut 14 is prevented from being rotated in the chamber 13 and also travelling toward the axis of said set screw 20.

-What is claimed is:

1. A variable resistor comprising a narrow housing of electric insulating material having an attachment face extending in the lengthwise direction thereof, a flat plate of electrical resistance material mounted on said attachment face, a stationary contacting member of electric conductive material mounted on said attachment face, an operating lever swingable over said attachment face and extending outside of said housing, and a movable slider of electric conductive material having two arms extending to the resistance plate and stationary contacting member, one of which has a contact element slidable on the surface of said resistance plate along the locus of said contact element with the movement of said operating lever, and the other of which has a contact element slidable on the surface of said stationary contacting member with the movement of the aforesaid contact element.

2. A variable resistor claimed in claim 1 in which said stationary contacting member is corrugated in its lengthwise direction so that the corresponding contact element is brought into the root portion of the corrugation thereof after passing over the crest portion.

3. A variable resistor claimed in claim 1 in which said narrow housing comprises a side wall and a peripheral wall integrally formed with said side wall in a manner substantially to surround the hollow portion of the housing, and there is provided a metal cover plate attached to the surface of the housing opposite to the side wall so as to shield the electric elements contained in the hollow portion from harmful electric effect from the outside of the housing.

4. A variable resistor claimed in claim 2 in Which said narrow housing comprises a side wall and a peripheral wall integrally formed with said side wall in a manner substantially to surround the hollow portion of the housing, and there is provided a metal cover plate attached to the surface of the housing opposite to the side wall so as to shield the electric elements contained in the hollow portion from harmful electric effect from the outside of the housing.

5. A variable resistor claimed in claim 1 in which said narrow housing comprises a side wall and a peripheral wall integrally formed with said side wall in a manner substantially to surround the hollow portion of the housing and includes recesses extending from the upper surface of the housing into the body thereof, chambers extending from the surface of the housing opposite to the side wall into the body and across the intermediate portion of the recess, and nuts contained in said chambers respectively.

6. A variable resistor claimed in claim 2 in which said narrow housing comprises a side wall and a peripheral wall integrally formed with said side wall in a manner substantially to surround the hollow portion of the housing and includes recesses extending from the upper surface of the housing into the body thereof, chambers extending from the usrface of the housing opposite to the side wall into the body and across the intermediate portion of the recess, and nuts contained in said chambers respectively.

7. A variable resistor claimed in claim 1 in which said movable slider is made of copper alloy having a suflicient elasticity in order to cause the contact elements to contact the resistance plate and contacting member as tightly as possible.

8. A variable resistor claimed in claim 2 in which said movable slider is made of copper alloy having a suflicient elasticity in order to cause the contact elements to contact the resistance plate and contacting member as tightly as possible.

9. A variable resistor claimed in claim 1 in which said movable slider is made of copper alloy having a suflicient elasticity in order to cause the contact elements to contact the resistance plate and contacting member as tightly as possible, and said narrow housing comprises a side wall and a peripheral wall integrally formed with said side wall in a manner substantially to surround the hollow portion of the housing, and there are provided a metal cover plate attached to the surface of the housing opposite to the side wall so as to shield the electric elements contained in the hollow portion from harmful electric eifect from the outside of the housing, and a protrusion formed at the inner end of the lever and slidably pressed on the inner surface of the cover plate by the elastic force of the movable slider.

10. A variable resistor claimed in claim 2 in which said movable slider is made of copper alloy having a sufiicient elasticity in order to cause the contact elements to contact the resistance plate and contacting member as tightly as possible, and said narrow housing comprises a side Wall and a peripheral wall integrally formed with said side wall in a manner substantially to surround the hollow portion of the housing, and there are provided a metal cover plate 6 attached to the surafce of the housing opposite to the side wall so as to shield the electric elements contained in the hollow portion from harmful electric effect from the outside of the housing, and a protrusion formed at the inner end of the lever and slidably pressed on the inner surface of the cover plate by the elastic force of the movable slider.

References Cited UNITED STATES PATENTS 1,519,591 12/1924 Perry 338175 2,617,911 11/1952 Carey et al 3355-165X LEWIS H. MYERS, Primary Examiner D. A. TONE, Assistant Examiner US. Cl. X.R. 338184 

